That may be the result of a stuck shed, which then pulled off good skin during the next shed or perhaps some kind of injury. Clean it with chlorhexadine or betadine and cover it with plain neosporin (with no painkillers added). Keep the gecko on paper towel substrate until healed and then make sure that it has proper humidity for future sheds.
The more serious issue that I see here is the emaciated condition of the gecko. I would recommend feeding it the Pangea With Insects crested gecko diet (offered every day) along with well gut loaded and dusted insects (crickets and roaches are good choices) a few times per week but not so much that it doesn't eat the CGD. It is very important that the gecko get the nutrients that are in the CGD.
If the gecko has been on a good diet for several months time already, I would take it to a vet for a fecal check as it should not still be so thin.
This is what I was thinking as well. I have been keeping the humidity up and keeping everything clean. I just found a herp vet near me and we will call tomorrow when they open. Thank you.